NeuroRehabilitation ELSEVIER
NeuroRehabilitation 8 (1997) 193-200
Somatoform pain disorder Fran~ois
M. Mai*
Department of Psychiatry, Ottawa General Hospital, 501 Smyth Road, Ottawa, Ontario K1 H 8L6, Canada
Abstract Chronic pain is common; it is found in up to 15% of randomly selected population samples, and psychosocial factors including those provoked by physical trauma associated with industrial and motor vehicular accidents are very common in etiology. The diagnosis of post-traumatic stress disorder may be appropriate in many of these cases. The objectives of this paper are to review the psychological and social factors which contribute to the etiology of chronic pain syndromes. It reviews also the relationship of pain to Depressive, Anxiety and Substance Abuse Disorders and the principles of management of Pain Disorder. Supportive psychotherapy, pharmacotherapy (in particular tricyclic antidepressant medication) and behavioral rehabilitation programs may all be helpful in producing symptomatic improvement. An interdisciplinary pain clinic, particularly one which involves non-medical health professionals such as psychologists, social workers, occupational therapists and physiotherapists are very helpful in the management of complex cases. © 1997 Elsevier Science Ireland Ltd.
Keywords: Pain; Somatoform; Psychogenic pain
1. Introduction
'Somatoform' is a neologism introduced by the authors of DSM III to describe a group of conditions which suggest or have the appearance of somatic disease. The philosophy behind successive DSM classificatory systems has become progressively more phenomenological, and progressively less etiological. This development is reflected in the transformation of 'Psychogenic' Pain * Corresponding author. Tel.: 7399980.
+ 1 613 7378764; fax: + I 613
Disorder of DSM III in 1980 into 'Somatoform' Pain Disorder of DSM III R in 1987 and simply 'Pain' Disorder of DSM IV [1]. It is doubtful whether these terminological changes are based on a progress in knowledge, or whether they have improved our understanding of the condition. DSM IV (1994) describes five somatoform conditions: Somatization disorder, Conversion disorder, Pain disorder, Hypochondriasis and Body dysmorphic disorder [1]. The features they share in common are that there is a physical symptom (or symptoms) suggestive of a physical disorder for which there is inadequate biological explanation. In addition, the symptom is not under volun-
1053·8135/97/$17.00 © 1997 Elsevier Science Ireland Ltd. All rights reserved.
PIIS1053-8135(96)00223-0
194
F.M. Mai / NeuroRehabilitation 8 (1997) 193-200
tary control and it causes impairment of social or . occupational functioning. DSM IV defines Pain Disorder as a condition in which pain is the predominant focus of clinical presentation. While not included in the diagnostic term, criteria 'C' states that 'psychological factors are judged to have an important role in the onset, severity, exacerbation or maintenance of the pain'. The criteria also specify that the pain is not feigned, and that it is 'not better accounted for' by mood, anxiety or psychotic disorder. Finally DSM defines 'chronic' pain as having a duration of 6 months or longer. Chronic pain is a common clinical problem and patients with chronic pain place substantial demands on the health care and social systems. A widely cited epidemiological study has shown that 15% of a randomly selected population sample suffers from chronic pain [2]. A more recent survey found a prevalence of 11.5% of somatisation syndrome (in which pain is a prominent symptom) [3]. This study also emphasized the strong tendency of this condition to be chronic. Although any part of the body may be affected, the back, head and neck are the most frequent anatomic regions affected by chronic pain syndromes, with the face and abdomen also commonly involved. In this paper, I propose to discuss the psychological and social factors which contribute to the etiology of chronic pain syndromes. The literature on these factors will be reviewed and I will include comments and conclusions based on extensive personal clinical experience with pain patients over a 3D-year period. An understanding of the psychopathology (the psychosocial factors which contribute to the development of a condition) is essential to rational and effective clinical management of chronic pain. I will discuss also the relationship of pain to Depressive, Anxiety and Substance Abuse Disorders and will end by outlining some principles of management of these conditions. It should be noted that the diagnosis of 'psychogenic' pain is not made solely by ruling out organic conditions. It is suspected, while conducting an assessment clinical interview, by identifying the presence of psychosocial events, conditions or circumstances which may have a cause-
effect relationship with the pain symptom. The diagnosis is then confirmed by finding inadequate or inconsistent signs on physical examination or special investigation. 2. The psychopathology of chronic pain
Merskey et al. (1979) have defined pain as 'an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such tissue damage' [4]. This is an excellent definition in that it emphasizes that pain is fundamentally a subjective experience, and cannot therefore be shared with anyone else. This fact makes the clinical evaluation of pain a uniquely complex endeavor. Its severity and its quality cannot be measured objectively; the clinician is dependant entirely on the subjective description by the sufferer, with the inherent biases and distortions which accompany subjectivity. This definition emphasises also that pain is associated with actual or potential tissue damage. Again this brings into focus the important role which subjective, emotional factors can play in the experience and in the description of pain. The gate control theory developed by Melzack and Wall similarly incorporates a substantial role for cerebral and psychogenic factors into its structure [5,6]. In a now classic paper, Engel well described the role of psychological factors, including childhood developmental variables related to aggression, punishment and guilt, to adult susceptibility to pain [7]. His hypotheses have been supported in a more recently published controlled study [8]. Perhaps the one limitation of Merskey's definition of pain is that it leaves out the social context of pain. We have all experienced pain, hence we know, from our own experience, something of what the patient is describing. We know it also as distressing, a symptom which requires immediate if not urgent removal. Pain has an impact, therefore, on others, and its non-removal by treatment causes distress in the social ecosystem of the sufferer. The feedback reaction from this ecosystem will itself have an effect on the experience and the complaints of the pain patient which can increase social withdrawal and loss of role [9].
F.M. Mai / NellroRehabilitation 8 (1997) 193-200
The end result of this vicious cycle can have a devastating effect on the chronic pain patient and his/her family. There are other examples of the role of psychological influence in modulating pain experience. Most striking are seen in individuals who sustain serious injuries in the heat of battle, or of a sport, yet who are able to continue active combat. Similarly, on the reverse side of this coin, is the individual who sustains a relatively minor injury in a motor vehicle accident with no discernible objective physical signs, but who becomes a years' long, or even a life-long invalid as a result. Chronic pain nearly always begins with acute pain provoked by an injury or by a disease process. In the majority of cases, the injury or disease subsides or is treated, the patient recovers and the pain disappears. Why do some individuals recover quickly from such tissue damage, and others develop chronic, recurrent or progressive pain syndromes? Because many chronic pain patients have little objective evidence of related tissue damage, it seems probable that psychosocial rather than biological factors playa key role in influencing this process. As Engel described, an individual's previous experience of pain, either in their personal life or in someone close to them, may play a key role in influencing the course and progress of the symptom [7]. The way that the individual is treated during the early developmental phase, can also play an important role. If, for example, the patient is dealt with in a brusque, indulgent or patronising manner, anger or resentment may be provoked which will reinforce the individual's complaining behavior. Similarly it has been shown also that a pain patient's spouse can have a strong impact on the maintenance of chronic pain [10-12]. The topic of secondary 'gain' is important but commonly misunderstood. The term secondary 'reinforcement' is preferable to 'gain', as the latter implies conscious manipulation which is present only in the malingerer. The process is best understood using a learning theory model in which an individual, through personal experience, develops behavioral characteristics associated with be-
195
ing ill. 'Illness behavior' was a term introduced by Mechanic to describe the behavior displayed by individuals in reaction to their perception of symptoms and health problems [13]. Illness behavior may be reinforced unwittingly by interpersonal, including medical professional, relationships. If this occurs at certain crucial times after a relatively minor injury, for example, a behavior pattern may be set which easily becomes perpetuated. Mention must be made at this point concerning the role of compensation in chronic pain syndromes. Physicians' attitudes towards compensation have fluctuated between extremes of stating, on the one hand, that it explains the entire clinical problem, and that the patient will recover once the compensation is settled [14] to the other extreme, where the existence of compensation is considered irrelevant [15,16] Shapiro and Roth reviewed the literature on the psychological, including particularly the litigation aspects of whiplash injuries and concluded that whiplash was a 'physical disorder', and that psychological and compensation factors contributed little to its etiology [16]. They found little ~upport for the conclusion that whiplash pain resolved once litigation was settled. Mayou in an excellent recent review, recommends that the terms 'compensation' or 'accident' neurosis should be discarded, and that the compensation issue should merely be regarded as one of the psychosocial factors which affect chronicity in pain syndromes [17]. He emphasizes that much could be accomplished, including a reduction in financial claims, if 'legal and insurance processes recognise suffering and respond quickly, effectively and courteously'. Many patients with pain syndromes following motor vehicle and industrial accidents display anger and a 'sense of injury' or grievance towards the perpetrator of the accident, or towards organisations such as insurance companies, and the Worker's Compensation Board. These grievances may be justified or they may be based on the present reality of the adversarial nature and the delays of our legal system, or they may be elaborations or exaggerations of relatively minor events. Whatever the underlying situation may be,
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the anger is a reality which may have a profound effect on the severity and the chronicity of the clinical syndrome. These features suggest that many patients with 'compensation' or 'accident' neurosis fit the criteria of a post-traumatic stress disorder (PTSD). They have been exposed to a traumatic event, and even though it may have been relatively minor, it may be perceived by the patient as being serious, or at least potentially so. They may also reexperience the event, avoid stimuli associated with it, and develop other symptoms not present before the trauma all features characteristic of PTSD. A recently published review found that PTSD was present in 'roughly' 10% of victims of motor vehicle accidents [18]. The diagnosis of PTSD for these patients may remove inappropriate overtones suggested by the words 'compensation' and 'accident'. It may also assist in the management of the patients who are often distressed and severely dysfunctional. This observation is supported by the finding that pain patiepts who are on compensation can benefit from intensive rehabilitation programs [15]. Other psychiatric conditions contribute to chronic pain syndromes, in particular Depressive disorder, Anxiety states and Substance Abuse. I would like to discuss each of these separately. It should be noted that these conditions are not necessarily mutually exclusive; they may overlap with each other and with the above mentioned points discussed in 'psychopathology'. 3. Depression There is a close aSSOCiatIOn between chronic pain and depression. Somatic symptoms including pain, are common in patients who are clinically depressed. The mechanism of this interaction is unclear; however, it may be related to reduced threshold and increased preoccupation with the self, which are common characteristics of depressed patients. Similarly, patients with chronic pain very commonly become clinically depressed. A genetic predisposition was suggested by Magni who found that a high proportion of pain patients had a family history of depression [19]. Alterations in neurotransmitter function af-
fecting both pain and depression pathways may also play a role in this interaction. The evidence in favor of a biochemical association between chronic pain syndromes and depression comes mainly from the proven efficacy of antidepressant medication in chronic pain patients [20]. However there is evidence that antidepressants (in particular tricyclics with a mixed serotonergic/noradrenergic action) are effective analgesics even in the absence of clinical depression [21]. It should be noted that the subjective symptom of 'depression' or sadness is not always present and is not itself a requirement for the diagnosis of depression. The patient may describe more general feelings of emotional distress or irritability or the depressed mood may be inferred by observation of the patient's expression, speech or behavior. Other features of depression, such as loss of interest or initiative, appetite, weight, energy, libido and pleasurable interests and activities will also be present. 4. Anxiety
Pain may feature in anxiety disorders allegedly because of the increase in muscle tension or spasm which occurs or because of the generalized increase in psychophysiologic arousal. This may be the mechanism in headache, post-infarct precordial pain and other pain syndromes affecting the musculoskeletal system. However recent evidence does not support the finding of increased muscle tension in these conditions [22]. Anxiety and Panic Disorders are particularly liable to occur in association with precordial chest pain syndromes [23]. The mechanism of production of the pain is not clear. Other somatic symptoms that are associated with physiologic and autonomic arousal (such as palpitations, sweating and tremor) are common and should be sought as part of the clinical inquiry. Generalized anxiety disorder, post-traumatic stress disorder and phobic disorder are other psychiatric conditions which may lead to pain symptoms.
F.M. Mai
I NeuroRehabilitation 8 (1997) 193-200
5. Substance abuse Chronic pain patients commonly are dependent on analgesic drugs. Although they are taken ostensibly to 'relieve' the pain, they provide little long-term relief, particularly if taken on a pm basis. Goldman has described the difficulties that occur when chronic pain patients are given longterm narcotics but, little has appeared in the literature on the role they play in the aggravation or perpetuation of pain [24]. This effect is likely based on the learning theory model described above. The complaint of pain is 'reinforced' by the temporary relief provided by the drug, only to recur when the effect of the drug wears off the withdrawal symptoms providing a further stimulus for analgesic use. This model does not rule out the possibility that there may be a previous or current pathophysiologic contributory factor which should be sought and treated in an appropriate manner. Dependence on benzodiazepines may also be a problem when the drug is used for the relief of anxiety associated with a regional pain such as headache or backache. 6. Management A primary principle of effective management is summarized in the ancient aphorism of Hippocrates, 'primus non nocere', that is, first do no harm. The pain of chronic pain patients may be aggravated by over zealous and invasive medical investigations and treatments, hence these should as far as possible be minimized. A second requirement is that a rational treatment program be based on a comprehensive psychosocial and medical evaluation so that appropriate treatments are applied to the psychosocial and medical aspects of the problem. Hence time should be spent with patients providing them with diagnostic information, using terms and concepts that they can understand, and answering questions in a factual manner. A comprehensive psychophysiologic framework in which the pain is attributed to both physical and psychologic factors will help the patient better understand the relevance of the latter. This approach will also assist and simplify
197
the referral of a patient to a psychiatrist if this is indicated. A team approach in a Pain Clinic, with representatives from specialties including physiatry, psychiatry, anesthesiology and neurology is often the best forum for managing complex cases. Two or more of these specialists may need to collaborate, and it is wise also to start with simpler, conservative treatment strategies, bearing in mind the need to base treatments on identified diagnostic problems. It should be noted that non-medical health professionals including psychologists, social workers, occupational therapists and physiotherapists all have a useful role in pain management Although some patients require a 'medicalmodel' approach to treatment, others are best helped by 'demedicalising' their therapy. An interdisciplinary team is in the best position to recommend which approach is best for individual patients. This section will focus on the role of the psychiatrist in the pain clinic, and in the mana.gement of chronic pain. Pain patients who may benefit from a psychiatric evaluation and possible therapy are those with symptoms of anxiety or depression, those with evidence of psychosocial stress or conflict and those in whom there appear to be insufficient organic factors to explain the pain. A Pain Clinic policy in which all patients referred to the clinic are assessed by the psychiatrist as part of the assessment workup is also useful as this defuses the defensiveness of patients who are reluctant to see a psychiatrist. Subsequently, a team decision can be made as to whether continuing psychiatric involvement is indicated. Both psychotherapy and pharmacotherapy play an important and complimentary role in the management of pain patients. Each of the topics will be discussed separately.
6.1. Psychotherapy Relatively little work has been done on the use of intensive psychotherapy in chronic pain patients [25]. Two studies found psychotherapy to be of limited value hence its use, alone, is likely inappropriate [26,27]. Nevertheless there are some basic principles of psychotherapy which need to
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F.M. Mai / NeuroRehabilitation 8 (1997) 193--200
be followed in the management of any patient with chronic pain. These include clarity of communication, continuity of care and general emotional support. Patients need have sufficient trust in the physician to verbalize personal concerns and ventilate emotional frustrations. The opportunity to do this in a supportive therapeutic relationship has therapeutic value in and of itself, even in the absence of any other therapeutic modalities. Sessions need to be regular (although not necessarily frequent) and structured. Pain patients sometimes alienate physicians and also their own social support network. If, despite this, they see their physician as being dependable in the longterm, it provides them with a much-needed anchor and will avoid the descending spiral which occurs with repeated specialist referrals and multiple physician involvement. Therapy sessions will provide the opportunity to deal with environmental stresses being experienced by the patient including conflict at home or in the workplace. It may be helpful also to meet with family members to ensure that they too have a clear understanding about the biopsychosocial aspects of the patient's condition as they may be inadvertently reinforcing the patient's illness behavior. It has been shown that involving the spouse in couple therapy improves outcome [28,29]. In the long run, a patient and consistent approach will pay substantial therapeutic dividends. Patients with more severe, chronic or disabling symptoms may require a more intensive behavioral approach using cognitive therapy, relaxation techniques, contingency reward or biofeedback. These may be administered on an outpatient, day-patient or inpatient basis. There is substantial evidence from the literature of the value of these approaches [30,31]. Bond and Hughes have provided an excellent description of the psychological aspects of pain and its treatment using behavioral techniques [32].
6.2. Pharmacotherapy The main pharmacologic agents used in the treatment of chronic pain patients are the antidepressant drugs. The is partly because many
patients are depressed clinically, but antidepressants may be effective even in those who are not depressed. There is evidence that they have an analgesic effect which is distinct from their antidepressant action [33]. This may be explained on the basis that there is a common biochemical mechanism which underlie both pain and depression. Additional evidence that the analgesic effects of antidepressants are distinct from the effect on mood is that they often are effective in smaller doses than those that are used to treat depression. Double blind studies suggest that the heterocyclic antidepressants are more effective in chronic pain than monoaminoxidase inhibitors or selective serotonin reuptake inhibitors [20,34]. Analgesics have a limited role in the treatment of chronic pain. The limitations are determined mainly by the fact that they all have the potential to be habit-forming. As a result, the tendency to take progressively increasing quantities becomes counterproductive in the long-term in a patient who does not have a limited life expectancy. In a series of three papers, Goldman described the problems that occur when chronic pain patients are given long-term narcotics. He described also the search for non-drug alternative treatments in this population [24]. If an analgesic is required, a non-narcotic type such as acetaminophen or a nonsteroidal anti-inflammatory agent such as ibuprofen or naproxen are most appropriate. In addition, the analgesic is best prescribed using a fixed-time format rather than an as-needed basis. This avoids the vicious cycle set up between the pain complaint and the relief or 'reward' which follows with the use of the analgesic. A fixed-dose format acts by preventing the development of pain rather than treating it when it occurs. Thus it is easier to control the total dosage, and dose escalation, which may occur when habit-forming drugs are given as-needed, is more easily avoided. If a patient is already taking analgesics on an as-needed basis, the first step in management is to change to a fixed-time format. Even though there may be no change in the total quantity used, this change alone often results in symptomatic improvement. It may then be possible to taper the dose gradually, either by reducing the
F.M. Mai
I
NeuroRehabilitation 8 (J997) 193-200
amount per dose or by gradually increasing the interval between doses, or both. This protocol must be followed only with the full understanding, approval and support of the patient. It may be helpful also to ask the patient to keep a daily diary indicating the time and the amount taken to promote compliance and to ensure that the protocol is followed. Anxiolytics have a limited role in chronic pain patients. Like analgesics, they are potentially habit-forming, and thus should be used for short periods only. If a patient has been using them on an as-needed basis for extended periods, the format is changed to fixed time without changing the total daily dose. It may then be possible to taper the total dose gradually. Barbiturates or barbiturate-containing drugs such as fiorinal should not be used in chronic pain because of their addictive properties, and their lethality if taken in overdose. 7. Summary and conclusions This paper describes the manifestations of 'Pain Disorder' as described by DSM IV. A description of the psychological and social factors which cause or aggravate pain syndromes is given. These include the individual's previous experience of pain, either in himself or in others, and the way his complaint is managed by others, including the immediate family and also physicians. Secondary 'reinforcement' (not 'gain') of the pain complaint may occur as a result of these experiences and relationships. Patients with pain associated with compensable injuries often experience anger and/or frustration towards the perceived perpetrators of the injury or towards insurance companies or Workman's Compensation Boards which may aggravate or help to perpetuate the pain experience. The anger and other clinical manifestations of these conditions have much in common with post-traumatic stress disorder; this diagnosis may make these conditions more comprehensible and may also assist in their management. Depression, Anxiety or Substance Abuse are frequently present in patients with chronic pain. The psychotherapeutic, behavior therapy and pharmacological therapies of chronic pain are
199
reviewed. Tricyclic antidepressants are of particular value, even in the absence of clinical depression. Patients with chronic pain syndromes present some of the most challenging problems in clinical medicine and they present also a substantial drain on the resources of the health care system. A rational psychological and medical approach in treatment can relieve symptoms and improve quality of life. References [1]
[2]
[3]
[4]
[5] [6]
[7] [8]
[9] [10]
[11]
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[16]
American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders. Fourth Edition. Washington. pp. 445-469. Crook J, Rideout E and Browne G. The prevalence of pain complaints in a general population. Pain 1984;18:299-314. Swartz M, Landerman R, George L, Blazer I and Escobar J. Somatisation Disorder in 'Psychiatric Disorders in America'. Robins L and Regier D, eds. Toronto: The Free Press, 1991 ;228. Merskey H, Albe-Fressard D, Bonica J. et al. Pain terms; a list with definitions and notes on usage. Pain 1979;6:249. Melzack R, Wall P: Pain mechanisms: a new theory. Science 1965;150:971. Melzack R: Physiology of Pain. Med North Am 1989;36:6524. Engel G: Psychogenic pain and the pain-prone patient. Am J Med 1959;26:899-918. Adler R, Zlot Set al. Engel's 'Psychogenic pain and the pain-prone patient': a retrospective, controlled clinical study. Psychosom Med 1989;51:87-101. Roy R: The Social Context of the Chronic Pain Sufferer. Toronto: University of Toronto Press, 1992;3-22. Kerns R, Haythornthwait J et al. The role of marital interaction in chronic pain and depressive symptom severity. J Psychosom Res 1990;34:401-408. Hughes A, Medley I, Turner G and Bond M. Psychogenic pain: a study of marital adjustment. Acta Psychiat Scand 1987;75:166-170. Turk D, Flor H and Rudy D: Pain and families I. Etiology, maintenance and psychosocial impact. Pain 1987;30:3-27. Mechanic D: The concept of illness behaviour. J Chron Dis 1972;15:189-194. Miller H: Accident neurosis. Br Med J 1961;919-998. Trabin T, Rader C, Cummings C: A comparison of pain management outcomes for disability compensation and non-compensation patients. Psychol Health 1987;1 :341-351. Shapiro A, Roth R. The cffcct of litigation on recovery from whiplash. Spine: State Art Rev 1993;7:531-556.
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[17] [18]
[19]
[20]
[21]
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[23]
[24] [25]
[26]
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Mayou R: Accident neurosis revisited. Br J Psychiatr 1996;168:399-403. Kuch K, Cox B, Evans R. Post-traumatic Stress Disorder and Motor Vehicle Accidents: A mUltidisciplinary overview. Can J Psychiatr 1996;41:429-434. Magni G. On the relationship between chronic pain and depression when there is no organic lesion. Pain 1987;31:1-22. Onghena P and Van Houdenhove. Antidepressant-induced analgesia in chronic non-malignant pain: a metaanalysis of 39 placebo-controlled studies. Pain 1992;49:205-220. Sawynok J and Reid A. Desipramine potentiates spinal antinociception by 5-hydroxytryptamine, morphine and odenosive. Pain 1992;50:113-118. Martin P, Marie G, Nathan P. Psychophysiological mechanisms in chronic headaches: investigation using pain induction and pain reduction procedures. J Psychosom Res 1992;36:137-148. Bass C and Mayou R. Chest pain and palpitations. In: Mayou R, Bass C and Sharpe M, eds. Treatment of Functional Somatic Symptoms, Oxford: Oxford University Press, 1995;328-352. Goldman B. Chronic pain and the search for alternative treatments. Can Med Assoc J 1991;145:508. Tunks E and Merskey H. Psychotherapy in the management of chronic pain. In: Bonica J, ed. The Management of Pain, 2nd edn., Philadelphia: Lea & Febiger, 1990;1751-1756. Bassett D and Pilowski I. A study of brief psychotherapy for chronic pain. J. Psychosom Res 1985;29:259-264.
[27]
[28]
[29]
[30]
[31]
[32] [33] [34]
[35]
Pilowsky I and Barrow C. A controlled study of psychotherapy and amitriptyline used individually and in combination in the treatment of chronic intractable 'psychogenic' pain. Pain 1990;40:3-19. Moore J and Chaney E. Outpatient group treatment of chronic pain: effects of spouse involvement. J Consult elin Psychol 1985;53:326-334. Saarijiirvi S, Alanen E et al. Couple therapy improves mental well-being in chronic low back pain patients - a controlled, five year follow up study. J Psychosom Res 1992;36:651-656. Spinhoven P and Linssen A: Behavioral treatment of chronic low back pain. I. Relation of coping strategy use to outcome. Pain 1991;45:29-34. Nicholas M, Wilson P and Goyen J. Comparison of cognitive-behavioral group treatment and an alternative non-psychological treatment for chronic low back pain. Pain 1992;48:339-347. Bond M and Hughes A: Psychological aspects of chronic pain. Int Rehab Med Int Disabil Stud 1987;9:23-27. Feinmann C: Pain relief by antidepressants: possible modes of action. Pain 1985;23:1-8. Max M, Lynch S, Muir J et al. Effects of desipramine, amitriptyline, and fluoxetine on pain in diabetic neuropathy. New Engl J Med 1992;326:1250-1256. Mendelson G: Not 'cured by a verdict'. Effects of legal settlement on compensation claimants. Med J Aus 1982;2:219-230.
NeuroRehabilitation 8 (1997) 193-200
Somatoform pain disorder Fran~ois
M. Mai*
Department of Psychiatry, Ottawa General Hospital, 501 Smyth Road, Ottawa, Ontario K1 H 8L6, Canada
Abstract Chronic pain is common; it is found in up to 15% of randomly selected population samples, and psychosocial factors including those provoked by physical trauma associated with industrial and motor vehicular accidents are very common in etiology. The diagnosis of post-traumatic stress disorder may be appropriate in many of these cases. The objectives of this paper are to review the psychological and social factors which contribute to the etiology of chronic pain syndromes. It reviews also the relationship of pain to Depressive, Anxiety and Substance Abuse Disorders and the principles of management of Pain Disorder. Supportive psychotherapy, pharmacotherapy (in particular tricyclic antidepressant medication) and behavioral rehabilitation programs may all be helpful in producing symptomatic improvement. An interdisciplinary pain clinic, particularly one which involves non-medical health professionals such as psychologists, social workers, occupational therapists and physiotherapists are very helpful in the management of complex cases. © 1997 Elsevier Science Ireland Ltd.
Keywords: Pain; Somatoform; Psychogenic pain
1. Introduction
'Somatoform' is a neologism introduced by the authors of DSM III to describe a group of conditions which suggest or have the appearance of somatic disease. The philosophy behind successive DSM classificatory systems has become progressively more phenomenological, and progressively less etiological. This development is reflected in the transformation of 'Psychogenic' Pain * Corresponding author. Tel.: 7399980.
+ 1 613 7378764; fax: + I 613
Disorder of DSM III in 1980 into 'Somatoform' Pain Disorder of DSM III R in 1987 and simply 'Pain' Disorder of DSM IV [1]. It is doubtful whether these terminological changes are based on a progress in knowledge, or whether they have improved our understanding of the condition. DSM IV (1994) describes five somatoform conditions: Somatization disorder, Conversion disorder, Pain disorder, Hypochondriasis and Body dysmorphic disorder [1]. The features they share in common are that there is a physical symptom (or symptoms) suggestive of a physical disorder for which there is inadequate biological explanation. In addition, the symptom is not under volun-
1053·8135/97/$17.00 © 1997 Elsevier Science Ireland Ltd. All rights reserved.
PIIS1053-8135(96)00223-0
194
F.M. Mai / NeuroRehabilitation 8 (1997) 193-200
tary control and it causes impairment of social or . occupational functioning. DSM IV defines Pain Disorder as a condition in which pain is the predominant focus of clinical presentation. While not included in the diagnostic term, criteria 'C' states that 'psychological factors are judged to have an important role in the onset, severity, exacerbation or maintenance of the pain'. The criteria also specify that the pain is not feigned, and that it is 'not better accounted for' by mood, anxiety or psychotic disorder. Finally DSM defines 'chronic' pain as having a duration of 6 months or longer. Chronic pain is a common clinical problem and patients with chronic pain place substantial demands on the health care and social systems. A widely cited epidemiological study has shown that 15% of a randomly selected population sample suffers from chronic pain [2]. A more recent survey found a prevalence of 11.5% of somatisation syndrome (in which pain is a prominent symptom) [3]. This study also emphasized the strong tendency of this condition to be chronic. Although any part of the body may be affected, the back, head and neck are the most frequent anatomic regions affected by chronic pain syndromes, with the face and abdomen also commonly involved. In this paper, I propose to discuss the psychological and social factors which contribute to the etiology of chronic pain syndromes. The literature on these factors will be reviewed and I will include comments and conclusions based on extensive personal clinical experience with pain patients over a 3D-year period. An understanding of the psychopathology (the psychosocial factors which contribute to the development of a condition) is essential to rational and effective clinical management of chronic pain. I will discuss also the relationship of pain to Depressive, Anxiety and Substance Abuse Disorders and will end by outlining some principles of management of these conditions. It should be noted that the diagnosis of 'psychogenic' pain is not made solely by ruling out organic conditions. It is suspected, while conducting an assessment clinical interview, by identifying the presence of psychosocial events, conditions or circumstances which may have a cause-
effect relationship with the pain symptom. The diagnosis is then confirmed by finding inadequate or inconsistent signs on physical examination or special investigation. 2. The psychopathology of chronic pain
Merskey et al. (1979) have defined pain as 'an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such tissue damage' [4]. This is an excellent definition in that it emphasizes that pain is fundamentally a subjective experience, and cannot therefore be shared with anyone else. This fact makes the clinical evaluation of pain a uniquely complex endeavor. Its severity and its quality cannot be measured objectively; the clinician is dependant entirely on the subjective description by the sufferer, with the inherent biases and distortions which accompany subjectivity. This definition emphasises also that pain is associated with actual or potential tissue damage. Again this brings into focus the important role which subjective, emotional factors can play in the experience and in the description of pain. The gate control theory developed by Melzack and Wall similarly incorporates a substantial role for cerebral and psychogenic factors into its structure [5,6]. In a now classic paper, Engel well described the role of psychological factors, including childhood developmental variables related to aggression, punishment and guilt, to adult susceptibility to pain [7]. His hypotheses have been supported in a more recently published controlled study [8]. Perhaps the one limitation of Merskey's definition of pain is that it leaves out the social context of pain. We have all experienced pain, hence we know, from our own experience, something of what the patient is describing. We know it also as distressing, a symptom which requires immediate if not urgent removal. Pain has an impact, therefore, on others, and its non-removal by treatment causes distress in the social ecosystem of the sufferer. The feedback reaction from this ecosystem will itself have an effect on the experience and the complaints of the pain patient which can increase social withdrawal and loss of role [9].
F.M. Mai / NellroRehabilitation 8 (1997) 193-200
The end result of this vicious cycle can have a devastating effect on the chronic pain patient and his/her family. There are other examples of the role of psychological influence in modulating pain experience. Most striking are seen in individuals who sustain serious injuries in the heat of battle, or of a sport, yet who are able to continue active combat. Similarly, on the reverse side of this coin, is the individual who sustains a relatively minor injury in a motor vehicle accident with no discernible objective physical signs, but who becomes a years' long, or even a life-long invalid as a result. Chronic pain nearly always begins with acute pain provoked by an injury or by a disease process. In the majority of cases, the injury or disease subsides or is treated, the patient recovers and the pain disappears. Why do some individuals recover quickly from such tissue damage, and others develop chronic, recurrent or progressive pain syndromes? Because many chronic pain patients have little objective evidence of related tissue damage, it seems probable that psychosocial rather than biological factors playa key role in influencing this process. As Engel described, an individual's previous experience of pain, either in their personal life or in someone close to them, may play a key role in influencing the course and progress of the symptom [7]. The way that the individual is treated during the early developmental phase, can also play an important role. If, for example, the patient is dealt with in a brusque, indulgent or patronising manner, anger or resentment may be provoked which will reinforce the individual's complaining behavior. Similarly it has been shown also that a pain patient's spouse can have a strong impact on the maintenance of chronic pain [10-12]. The topic of secondary 'gain' is important but commonly misunderstood. The term secondary 'reinforcement' is preferable to 'gain', as the latter implies conscious manipulation which is present only in the malingerer. The process is best understood using a learning theory model in which an individual, through personal experience, develops behavioral characteristics associated with be-
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ing ill. 'Illness behavior' was a term introduced by Mechanic to describe the behavior displayed by individuals in reaction to their perception of symptoms and health problems [13]. Illness behavior may be reinforced unwittingly by interpersonal, including medical professional, relationships. If this occurs at certain crucial times after a relatively minor injury, for example, a behavior pattern may be set which easily becomes perpetuated. Mention must be made at this point concerning the role of compensation in chronic pain syndromes. Physicians' attitudes towards compensation have fluctuated between extremes of stating, on the one hand, that it explains the entire clinical problem, and that the patient will recover once the compensation is settled [14] to the other extreme, where the existence of compensation is considered irrelevant [15,16] Shapiro and Roth reviewed the literature on the psychological, including particularly the litigation aspects of whiplash injuries and concluded that whiplash was a 'physical disorder', and that psychological and compensation factors contributed little to its etiology [16]. They found little ~upport for the conclusion that whiplash pain resolved once litigation was settled. Mayou in an excellent recent review, recommends that the terms 'compensation' or 'accident' neurosis should be discarded, and that the compensation issue should merely be regarded as one of the psychosocial factors which affect chronicity in pain syndromes [17]. He emphasizes that much could be accomplished, including a reduction in financial claims, if 'legal and insurance processes recognise suffering and respond quickly, effectively and courteously'. Many patients with pain syndromes following motor vehicle and industrial accidents display anger and a 'sense of injury' or grievance towards the perpetrator of the accident, or towards organisations such as insurance companies, and the Worker's Compensation Board. These grievances may be justified or they may be based on the present reality of the adversarial nature and the delays of our legal system, or they may be elaborations or exaggerations of relatively minor events. Whatever the underlying situation may be,
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the anger is a reality which may have a profound effect on the severity and the chronicity of the clinical syndrome. These features suggest that many patients with 'compensation' or 'accident' neurosis fit the criteria of a post-traumatic stress disorder (PTSD). They have been exposed to a traumatic event, and even though it may have been relatively minor, it may be perceived by the patient as being serious, or at least potentially so. They may also reexperience the event, avoid stimuli associated with it, and develop other symptoms not present before the trauma all features characteristic of PTSD. A recently published review found that PTSD was present in 'roughly' 10% of victims of motor vehicle accidents [18]. The diagnosis of PTSD for these patients may remove inappropriate overtones suggested by the words 'compensation' and 'accident'. It may also assist in the management of the patients who are often distressed and severely dysfunctional. This observation is supported by the finding that pain patiepts who are on compensation can benefit from intensive rehabilitation programs [15]. Other psychiatric conditions contribute to chronic pain syndromes, in particular Depressive disorder, Anxiety states and Substance Abuse. I would like to discuss each of these separately. It should be noted that these conditions are not necessarily mutually exclusive; they may overlap with each other and with the above mentioned points discussed in 'psychopathology'. 3. Depression There is a close aSSOCiatIOn between chronic pain and depression. Somatic symptoms including pain, are common in patients who are clinically depressed. The mechanism of this interaction is unclear; however, it may be related to reduced threshold and increased preoccupation with the self, which are common characteristics of depressed patients. Similarly, patients with chronic pain very commonly become clinically depressed. A genetic predisposition was suggested by Magni who found that a high proportion of pain patients had a family history of depression [19]. Alterations in neurotransmitter function af-
fecting both pain and depression pathways may also play a role in this interaction. The evidence in favor of a biochemical association between chronic pain syndromes and depression comes mainly from the proven efficacy of antidepressant medication in chronic pain patients [20]. However there is evidence that antidepressants (in particular tricyclics with a mixed serotonergic/noradrenergic action) are effective analgesics even in the absence of clinical depression [21]. It should be noted that the subjective symptom of 'depression' or sadness is not always present and is not itself a requirement for the diagnosis of depression. The patient may describe more general feelings of emotional distress or irritability or the depressed mood may be inferred by observation of the patient's expression, speech or behavior. Other features of depression, such as loss of interest or initiative, appetite, weight, energy, libido and pleasurable interests and activities will also be present. 4. Anxiety
Pain may feature in anxiety disorders allegedly because of the increase in muscle tension or spasm which occurs or because of the generalized increase in psychophysiologic arousal. This may be the mechanism in headache, post-infarct precordial pain and other pain syndromes affecting the musculoskeletal system. However recent evidence does not support the finding of increased muscle tension in these conditions [22]. Anxiety and Panic Disorders are particularly liable to occur in association with precordial chest pain syndromes [23]. The mechanism of production of the pain is not clear. Other somatic symptoms that are associated with physiologic and autonomic arousal (such as palpitations, sweating and tremor) are common and should be sought as part of the clinical inquiry. Generalized anxiety disorder, post-traumatic stress disorder and phobic disorder are other psychiatric conditions which may lead to pain symptoms.
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5. Substance abuse Chronic pain patients commonly are dependent on analgesic drugs. Although they are taken ostensibly to 'relieve' the pain, they provide little long-term relief, particularly if taken on a pm basis. Goldman has described the difficulties that occur when chronic pain patients are given longterm narcotics but, little has appeared in the literature on the role they play in the aggravation or perpetuation of pain [24]. This effect is likely based on the learning theory model described above. The complaint of pain is 'reinforced' by the temporary relief provided by the drug, only to recur when the effect of the drug wears off the withdrawal symptoms providing a further stimulus for analgesic use. This model does not rule out the possibility that there may be a previous or current pathophysiologic contributory factor which should be sought and treated in an appropriate manner. Dependence on benzodiazepines may also be a problem when the drug is used for the relief of anxiety associated with a regional pain such as headache or backache. 6. Management A primary principle of effective management is summarized in the ancient aphorism of Hippocrates, 'primus non nocere', that is, first do no harm. The pain of chronic pain patients may be aggravated by over zealous and invasive medical investigations and treatments, hence these should as far as possible be minimized. A second requirement is that a rational treatment program be based on a comprehensive psychosocial and medical evaluation so that appropriate treatments are applied to the psychosocial and medical aspects of the problem. Hence time should be spent with patients providing them with diagnostic information, using terms and concepts that they can understand, and answering questions in a factual manner. A comprehensive psychophysiologic framework in which the pain is attributed to both physical and psychologic factors will help the patient better understand the relevance of the latter. This approach will also assist and simplify
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the referral of a patient to a psychiatrist if this is indicated. A team approach in a Pain Clinic, with representatives from specialties including physiatry, psychiatry, anesthesiology and neurology is often the best forum for managing complex cases. Two or more of these specialists may need to collaborate, and it is wise also to start with simpler, conservative treatment strategies, bearing in mind the need to base treatments on identified diagnostic problems. It should be noted that non-medical health professionals including psychologists, social workers, occupational therapists and physiotherapists all have a useful role in pain management Although some patients require a 'medicalmodel' approach to treatment, others are best helped by 'demedicalising' their therapy. An interdisciplinary team is in the best position to recommend which approach is best for individual patients. This section will focus on the role of the psychiatrist in the pain clinic, and in the mana.gement of chronic pain. Pain patients who may benefit from a psychiatric evaluation and possible therapy are those with symptoms of anxiety or depression, those with evidence of psychosocial stress or conflict and those in whom there appear to be insufficient organic factors to explain the pain. A Pain Clinic policy in which all patients referred to the clinic are assessed by the psychiatrist as part of the assessment workup is also useful as this defuses the defensiveness of patients who are reluctant to see a psychiatrist. Subsequently, a team decision can be made as to whether continuing psychiatric involvement is indicated. Both psychotherapy and pharmacotherapy play an important and complimentary role in the management of pain patients. Each of the topics will be discussed separately.
6.1. Psychotherapy Relatively little work has been done on the use of intensive psychotherapy in chronic pain patients [25]. Two studies found psychotherapy to be of limited value hence its use, alone, is likely inappropriate [26,27]. Nevertheless there are some basic principles of psychotherapy which need to
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be followed in the management of any patient with chronic pain. These include clarity of communication, continuity of care and general emotional support. Patients need have sufficient trust in the physician to verbalize personal concerns and ventilate emotional frustrations. The opportunity to do this in a supportive therapeutic relationship has therapeutic value in and of itself, even in the absence of any other therapeutic modalities. Sessions need to be regular (although not necessarily frequent) and structured. Pain patients sometimes alienate physicians and also their own social support network. If, despite this, they see their physician as being dependable in the longterm, it provides them with a much-needed anchor and will avoid the descending spiral which occurs with repeated specialist referrals and multiple physician involvement. Therapy sessions will provide the opportunity to deal with environmental stresses being experienced by the patient including conflict at home or in the workplace. It may be helpful also to meet with family members to ensure that they too have a clear understanding about the biopsychosocial aspects of the patient's condition as they may be inadvertently reinforcing the patient's illness behavior. It has been shown that involving the spouse in couple therapy improves outcome [28,29]. In the long run, a patient and consistent approach will pay substantial therapeutic dividends. Patients with more severe, chronic or disabling symptoms may require a more intensive behavioral approach using cognitive therapy, relaxation techniques, contingency reward or biofeedback. These may be administered on an outpatient, day-patient or inpatient basis. There is substantial evidence from the literature of the value of these approaches [30,31]. Bond and Hughes have provided an excellent description of the psychological aspects of pain and its treatment using behavioral techniques [32].
6.2. Pharmacotherapy The main pharmacologic agents used in the treatment of chronic pain patients are the antidepressant drugs. The is partly because many
patients are depressed clinically, but antidepressants may be effective even in those who are not depressed. There is evidence that they have an analgesic effect which is distinct from their antidepressant action [33]. This may be explained on the basis that there is a common biochemical mechanism which underlie both pain and depression. Additional evidence that the analgesic effects of antidepressants are distinct from the effect on mood is that they often are effective in smaller doses than those that are used to treat depression. Double blind studies suggest that the heterocyclic antidepressants are more effective in chronic pain than monoaminoxidase inhibitors or selective serotonin reuptake inhibitors [20,34]. Analgesics have a limited role in the treatment of chronic pain. The limitations are determined mainly by the fact that they all have the potential to be habit-forming. As a result, the tendency to take progressively increasing quantities becomes counterproductive in the long-term in a patient who does not have a limited life expectancy. In a series of three papers, Goldman described the problems that occur when chronic pain patients are given long-term narcotics. He described also the search for non-drug alternative treatments in this population [24]. If an analgesic is required, a non-narcotic type such as acetaminophen or a nonsteroidal anti-inflammatory agent such as ibuprofen or naproxen are most appropriate. In addition, the analgesic is best prescribed using a fixed-time format rather than an as-needed basis. This avoids the vicious cycle set up between the pain complaint and the relief or 'reward' which follows with the use of the analgesic. A fixed-dose format acts by preventing the development of pain rather than treating it when it occurs. Thus it is easier to control the total dosage, and dose escalation, which may occur when habit-forming drugs are given as-needed, is more easily avoided. If a patient is already taking analgesics on an as-needed basis, the first step in management is to change to a fixed-time format. Even though there may be no change in the total quantity used, this change alone often results in symptomatic improvement. It may then be possible to taper the dose gradually, either by reducing the
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amount per dose or by gradually increasing the interval between doses, or both. This protocol must be followed only with the full understanding, approval and support of the patient. It may be helpful also to ask the patient to keep a daily diary indicating the time and the amount taken to promote compliance and to ensure that the protocol is followed. Anxiolytics have a limited role in chronic pain patients. Like analgesics, they are potentially habit-forming, and thus should be used for short periods only. If a patient has been using them on an as-needed basis for extended periods, the format is changed to fixed time without changing the total daily dose. It may then be possible to taper the total dose gradually. Barbiturates or barbiturate-containing drugs such as fiorinal should not be used in chronic pain because of their addictive properties, and their lethality if taken in overdose. 7. Summary and conclusions This paper describes the manifestations of 'Pain Disorder' as described by DSM IV. A description of the psychological and social factors which cause or aggravate pain syndromes is given. These include the individual's previous experience of pain, either in himself or in others, and the way his complaint is managed by others, including the immediate family and also physicians. Secondary 'reinforcement' (not 'gain') of the pain complaint may occur as a result of these experiences and relationships. Patients with pain associated with compensable injuries often experience anger and/or frustration towards the perceived perpetrators of the injury or towards insurance companies or Workman's Compensation Boards which may aggravate or help to perpetuate the pain experience. The anger and other clinical manifestations of these conditions have much in common with post-traumatic stress disorder; this diagnosis may make these conditions more comprehensible and may also assist in their management. Depression, Anxiety or Substance Abuse are frequently present in patients with chronic pain. The psychotherapeutic, behavior therapy and pharmacological therapies of chronic pain are
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reviewed. Tricyclic antidepressants are of particular value, even in the absence of clinical depression. Patients with chronic pain syndromes present some of the most challenging problems in clinical medicine and they present also a substantial drain on the resources of the health care system. A rational psychological and medical approach in treatment can relieve symptoms and improve quality of life. References [1]
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